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沙坝
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'''对于水泥的总体建议'''：A common cause of cracks in structures and linings (e.g. in tanks, dams, waterways, wells) is errors in mixing and applying the cement. First of all, it is important that only pure ingredients are used: clean water, clean sand, clean rocks. The materials have to be mixed very thoroughly. Secondly, the amount of water during mixing needs to minimal: the concrete or cement needs to be just workable, on the dry side even, and not fluid. Thirdly, it is essential that during curing the cement or concrete is kept moist at all times, for at least a week. Structures should be covered with plastic, large leaves or other materials during the curing period, and kept wet regularly. 建筑物产生裂缝（如，水槽、坝体、排水沟、井）的普遍原因是水泥混合和施用不当造成的。首先，只用纯净原料（干净的水、沙、石头），这一点至关重要。原料必须充分混合。第二，混合时需要的水量极小：混凝土或水泥能用即可，不稀且较干。第三，在固化过程中，水泥或混凝土至少一周都必须保持水分。在固化过程中，建筑物应该由塑料、大树叶或其它材料加以覆盖，保持水分。
'''Specific advice具体建议'''[[Image:SandDamConstruction.JPG|thumb|right|200px|Sand dam under construction. Somaliland. 建造中的沙坝。索马里兰。 Eric Fewster, BushProof / Caritas]][[Image:CompletedSandDam.JPG|thumb|right|200px|Completed sand dam. Somaliland. 竣工的沙坝。索马里兰。 Eric Fewster, BushProof / Caritas]]* Timing is important: dams should be built during the dry season, but don’t build dams too close to the rains in order to avoid the trench filling up with water or the dam being washed away.时间安排很重要：建坝需在旱季进行，且勿太临近雨季，以避免沟渠被水填满或坝体被冲走。* The method depends on the type of dam and the type of ground. The construction of sand dams in cascades improves total storage and efficiency and minimizes seepage losses. Dams made of concrete, stone-masonry (cheapest and easiest) and brickwork require skilled labour for construction, but are stronger and have a longer lifespan. 建坝方式由水坝类型和地质类型来决定。建造沙坝
* Usually sand dams are built onto a rock layer, but where there is no rock and only clay, it can still work but as long as the foundation is keyed into the clay layer and where the wall does not protrude more than 0.5m above original sand level, otherwise there is a risk the structure overturns during a flood event.
* Key into banks or construct wing walls to avoid erosion around edges of the sand dam. Where wing walls are built, a good technique is to start with the wing walls and work inwards to the centre, since community enthusiasm lags by the time wing walls are constructed (if not built first), yet they are essential to proper functioning. Length of the wing wall varies according to bank characteristic: loose riverbanks, 7 metres; hard soils, 5 metres; hard & impermeable soils or rocks, wing wall is not needed. Planting napier grass along upstream riverbanks controls erosion and fixes the course of the river in a flood.
